Field of Disclosure
Embodiments described herein are generally related to the field of thermal management in printed circuit board devices. More specifically, embodiments as disclosed herein are related to the field of thermal management in stators made on printed circuit boards for electric motors and generators.
Related Art
Current electric motors and other electric devices handling high currents through electrical leads in a printed circuit board (PCB) face multiple problems resulting from the large heat dissipation in the PCB. Some of the problems include warping of the substrate, which leads to mechanical failure and destructive mechanical interferences with the rotor of the motor or generator. Moreover, high temperature gradients in the PCB may lead to structural damage of the PCB such as delamination or localized failure of the electrical leads or the dielectric material in the substrate. The rare-earth magnets typically employed in airgap printed circuit board machines are also temperature sensitive. If the magnet temperature exceeds a specified value, the magnets can degrade and lose their magnetic field.
Printed circuit board electric machines built without the features described in this disclosure, i.e., the current state-of-the art, employ a variety of strategies to manage heat. Collectively, these strategies limit the commercial appeal and marketability of the basic printed circuit board stator design. These strategies include a) oversizing the machine relative to the desired mechanical operating portion so that the machine structure acts as a heat sink, b) actively cooling the machine, c) introduce efficiency compromising features such as larger air gaps between the rotor and the stator, d) limiting the machine to intermittent-duty applications, and/or e) equipping the machine with temperature-sensing controllers.